Intraductal papillomas are composed of papillary projections with fibrovascular cores, covered by an epithelial and myoepithelial layer [1]. While nearly one-third-is asymptomatic and discovered on radiological screening studies [2], papillomas represent between 3 and 9 % of annual biopsies [3]. Approximately 10 % of papillomas are multiples [4]. Multiple papillomas (MP) often have varying definitions and can be defined by two, three or five papillomas [4] or are not defined in most articles [5].

MP have a controversial risk of malignancy partly due to varied definitions. When looking at 54 patients with MP, including 13 with atypia, Lewis found risk of cancer was 3 to 7 times greater than that of the general population [4]. On the other hand, a few authors didn’t find an association with malignancy but only gathered 11 patients [6].

In addition to malignancy, MP can be recurrent and may lead to several surgeries [7]. If we exclude patients lost to follow-up, Ali-Fehmi found that 9 % (1/8) of MP with atypia, 19 % (3/16) of MP with ductal carcinoma in situ (DCIS), and 18 % (2/11) of MP with invasive carcinoma (IC) developed contralateral carcinoma, whereas none of MP without atypical lesion (AL) developed carcinoma nor ipsilateral recurrence [8].

The main purpose of this study is to estimate the risk of AL, carcinomas in situ (CIS) and/or IC associated with MP. The secondary objective intends to identify risk factors for AL, CIS, and/or IC, as well as the risk of recurrence associated with MP.